A engaged couple who wanted to lose weight so they could wrap their arms around each other during the first dance at their reception lost a staggering 328lbs between them - then called off their wedding at the last minute.

Shane Graves, 40, and Marissa Schnell, 32, from Plant City, Florida, were engaged for the last year of their seven year courtship, but the two, who never spent any time apart, put off their wedding because they knew they were extremely overweight. While 5'10" Marissa weighed 255lbs, Shane clocked in at 467lbs and was dubbed a 'heart attack waiting to happen'.

Marissa, who vowed to get healthier, wrote an impassioned letter to trainers Chris and Heidi Powell from the ABC reality show Extreme Weight Loss in hopes that the couple would take on their case and help her and her partner Shane change their unhealthy lifestyles and walk down the aisle once and for all - but only one of her dreams came true.

The couple met in 2007, and while Marissa admitted that she didn't like Shane at first, she cannot image her life without him now.

Last year, Shane won tickets to a private Jennifer Nettles concert and convinced the country start to help him propose during the Q&A session at the event.

However, Shane and Marissa have yet to make any wedding plans.

'I think that if we would have been healthy we would have been married a lot time ago,' she explained. 'We just put it off.'

It was also at a Jennifer Nettles concert that Chris and Heidi brought Shane and Marissa on stage and revealed that they were taking on their case.

Both Shane and Marissa have faced hardships that caused them to put on weight.

Marissa's father killed himself and during the course of her relationship with Shane, she was diagnosed with multiple sclerosis (MS) and went into a deep depression.

'I thought my life was over,' she explained. Meanwhile, Shane's began to gain massive amounts of weight after his first marriage started to deteriorate. When he tried to seek custody of his only child during their bitter divorce battle, he learned that his daughter wasn't biologically his.

Shane credited Marissa for making his 'life worth living'. However, Shane's weight was already out of control. He had to sleep with an oxygen mask on at night and Marissa had woken up multiple times to find that he wasn't breathing.

'I am killing myself just like her father did,' Shane told the cameras.

'I need you to change because I want you to be here,' Marissa told him. 'I want to have babies with you and grow old together.'

Marissa had already started her weight loss journey on her own, but had difficulty getting Shane, who desperately needed to shed pounds, on board.

Chris noted that Marissa was one of the smallest people they have worked and would have never taken her on if it wasn't for Shane's ailing health.

When Marissa learned that Shane weighed 467lbs, she said: 'It just breaks my heart. I feel like I enable him'.

After the split, Heidi visited Marissa in Ohio and learned that she cut her hair and moved in with her mom. She also started volunteering at a Suicide Prevention Center. Marissa explained that she was not dating, but added that 'it's fun being single'.

Meanwhile, Shane fell in love with Arizona and decided to move there. When Chris went to visit him he was worried that the breakup would cause him to turn to old habits, but when Shane opened the door, he looked thinner than ever.

Because of their breakup, Shane and Marissa did their final weigh-ins separately.

It was revealed that Marissa clocked in at 169lbs after losing a total of 89lbs, and Shane had whittled down to 225lbs, which qualified him for skin removal surgery. And his 242lb weight loss gave him the Extreme Weight Loss record of most weight lost in six months.